Robertson A G, Robertson C, Boyle P, Symonds R P, Wheldon T E
Beatson Oncology Centre, Western Infirmary, Glasgow.
Eur J Cancer. 1993;29A(4):501-10. doi: 10.1016/s0959-8049(05)80139-x.
Laryngeal tumours, especially T1N0M0 and T2N0M0 lesions, are readily controlled by radiotherapy. Studies have shown that control varies with the dose of radiotherapy delivered to the tumour. Other factors, including the dose per fraction and the time over which the treatment schedule is delivered are also important. The varying biological effectiveness of a number of different dose fraction time schedules used in the management of laryngeal tumours of different stages are considered, the end points being tumour control and associated morbidity. Special attention has been given to the length of time over which the schedule is delivered. Of the schedules examined the results would suggest that a dose of 60 Gy given in 25 fractions over a period of 35 days is the best of the six schedules studied for T1, T2, T3 and T4 lesions with minimal associated morbidity. It is possible, however, that the poor results shown on the Kaplan-Meier curves for patients treated with the schedule of 60 Gy in 30 fractions over a period of 42 days could be due to geographical misses of the tumours as 56% were treated without a beam directed shell. The poor result obtained when patients were treated with the schedule of 60 Gy given in 30 fractions over 49+ days may be due to tumour repopulation occurring during the rest period though the possibility of geographical misses may contribute to the poor tumour control results. Mathematical modelling using linear quadratic analysis suggests that the shorter the period of time over which the treatment is given the better chance of achieving tumour control irrespective of the stage of the disease. These models were developed for patients treated with a beam directed shell thus excluding those patients who are most likely to be at risk from a geographic miss of the tumour. Linear quadratic analysis of the treatment data suggests that the ratio alpha/beta for tumour cells is estimated in the region of 13 Gy. For T1 lesions the tumour doubling time is in the order of 6 days, with longer doubling times for the more advanced stages. The analysis provides some support for investigative use of accelerated treatment schedules. This analysis also shows the importance of using beam directed shells when treating small fields especially in the head and neck region.
喉肿瘤，尤其是T1N0M0和T2N0M0病变，很容易通过放射治疗得到控制。研究表明，控制效果随给予肿瘤的放射治疗剂量而变化。其他因素，包括每次分割剂量和治疗方案的实施时间也很重要。本文考虑了在不同分期喉肿瘤管理中使用的多种不同剂量分割时间方案的不同生物学效应，终点指标为肿瘤控制和相关并发症。特别关注了治疗方案的实施时间长度。在所研究的方案中，结果表明，对于T1、T2、T3和T4病变，在35天内分25次给予60 Gy的剂量是所研究的六种方案中最佳的，相关并发症最少。然而，对于在42天内分30次给予60 Gy方案治疗的患者，Kaplan-Meier曲线显示的不良结果可能是由于肿瘤的射野遗漏，因为56%的患者治疗时没有使用定向射野罩。当患者在49 +天内分30次给予60 Gy方案治疗时获得的不良结果可能是由于在休息期发生了肿瘤再增殖，尽管射野遗漏的可能性可能导致肿瘤控制效果不佳。使用线性二次分析的数学模型表明，无论疾病分期如何，治疗时间越短，实现肿瘤控制的机会越好。这些模型是为使用定向射野罩治疗的患者开发的，因此排除了那些最有可能因肿瘤射野遗漏而处于风险中的患者。对治疗数据的线性二次分析表明，肿瘤细胞的α/β比值估计在13 Gy左右。对于T1病变，肿瘤倍增时间约为6天，随着分期进展，倍增时间更长。该分析为加速治疗方案的研究应用提供了一些支持。该分析还表明，在治疗小射野时，尤其是在头颈部区域，使用定向射野罩的重要性。
